Electron discharge device



Filed Dec. 2. 1939 2 sheeis -sheet 1 //v VEN TOR S. 0. E/(STRAND A 7'TORNEY June 17, 1941.

S. O. EKST RAND ELECTRON DISCHARGE DEVICE Filed Dec., 2,1939:

2' Sheets-Sheet -2 AT TO RNEY Patented June 17, 19 41 UNITED STATESPATENT OFFICE 2,245,581 I smac'mon mscrmnoa nrvrcu State 0. Ekstrand,Bidgefleld Park, N. 1., assignor to Bell Telephone Laboratories,Incorporated, New York, N. Y., a corporation of New York ApplicationDecember 2, 1939, Serial No. 307,231

8 Claims. (01. 250-1152 This invention relates to electron dischargedevices and more particularly to cathode ray devices of the typedisclosed in the application Serial No. 387,232, filed S. Glass.

Cathoderay devices, such as shown in the above-identified application ofMyron 8. Glass, comprise in general an electron source, such as acathode, an electron receiving element, such as a fluorescent screen,spaced from the electron source, and an electrode system forconcentrating the electrons emanating from the source into a thin beamor pencil, for focussing the beam or pencil upon the screen and fordeflecting the beam whereby it traces a pattern upon: the electronreceiving element.

As pointed out in the Glass application, the desired concentrating andfoeussing of the electron beam may be achieved by a multielectrodecollimating system and a multielectrode focussing system, the variouselectrodes being of predetermined configuration and axially symmetricalwhereby axially symmetrical fields of particular contour and strengthare produced.

The number of electrodes involved entails mechanical diiflculties fromthe standpoint of construction and. furthermore, the complexity of theelectrode system renders dimcult the attainmentof accurate coaxiality ofthe electrodes which is requisite for the production of axiallysymmetrical fields.

One general object of this invention is to simplify the assembly ofmuitielectrode systems for cathodev raydevices. I

Another object of this invention is to expedite the mounting of theelectrodes of such systems in cathode ray devices.

A further object of this invention is to facilitate the accurate coaxialalignment of a plurality of electrodes in a collimating and focussingsystem for cathode ray devices.

Still another object of this invention is to shield eflectively thedeflector plates in cathode ray devices from extraneous'flelds.

In one illustrative embodiment of this invention, a cathode my devicecomprises anenclosing vessel having a stem at one end and a fluorescentscreen at the other end, and provided with a cylindrical column orstandard extending from adjacent the stem and coaxial therewith. Acathode is mounted adjacent the stem and a collimating system and afocussing system are disposed between the cathode and the screen, eachof these systems including a pair of axially symmetrical electrodes. Aplurality of deflector December 2, 1939,0f Myron plates are locatedbetween the focusing system and the screen.

' In accordance with one feature of this invention, the entire electrodesystem is fabricated in two unitary assemblies one of which is sup- 4ported from the stem and the other of which supported by the column orstandard.

comprises collimating and modulating electrodes and one of theelectrodes of the focussing system, and means are provided forautomatically locating these electrodes in accurate coaxial relationduring fabrication of the assembly.

In accordance with a further feature of this invention, the otherunitary assembly comprises pairs of deflector plates and'a plurality ofshields each enclosing a pair of the deflector plates.

The invention and the foregoing and other features thereof will beunderstood more clearly and fully from the following detaileddescription with reference to the accompanying drawings in which:

Fig. 1 is an elcvational view in perspective of a cathode ray dischargedevice illustrative of one embodiment of this invention, portions oftheenclosing vessel and of one of the terminal carrying bases being brokenaway to show the internal structure more clearly;

Fig. 2 is an end view of the device shown in Fig. 7

1, illustrating the arrangement of the terminals for the electrodes; v

Fig. 3 is an enlarged detail view, mainly in section, of the electrongun and deflector plate assembly included in the device shown in Fig. 1;

Fig. 4 is a plan view, partly in section along line 4-4 of Fig. 3, ofthe yillustrated in Fig. 3:

.Fig. 5 is, an enlarged detail elevational view, mainly in section, ofthe electron gun includ in the assembly shown in Fig. 3;

Fig. 6 is another enlarged detail view, in section, showing details ofthe oollimating electron; and

Figs. 7 and 8 are detail views of modifications of the deflector plateand shield assembly in the structure shown inFlg.3.

- ray device shown in Fig. 1 comprises an evacuated Referring now to thedrawings. the cathode tending stem II which terminates in a tri-armedpress It. The flaring end portion ll terminates in a dome-shaped wall15, the inner surface of which has thereon a fluorescent coating 16defining a screen. Portions of the inner surfaces of the tubular portionIn and flaring end portion H are coated with an opaque electricallyconductive material l1, such as colloidal graphite known commercially asAquadag," as described in Patent 2,096,416, granted October 19, 1937, toHoward W. Weinhart. Sealed-toan intermediate area of the reduced endportion I2 is an elongated cylindrical insulating column or standard l8coaxial with the stem l3. The column' or standard 18 may be, forexample, of glass and fused at one end to the inner wall of the reducedend portion I2.

Suitably afilxed to the end of the reduced cylindrical portion I2 is abase 19 carrying a plurality of terminal prongs 20 through whichelectrical connection may be established to certain of the electrodes ofthe device. A second base is ailixed to an intermediate portion of theenclosing vessel and comprises a metallic shell 2|, cemented to thevessel as indicated at 22, and an insulating disc 23, which carries aplurality of terminal prongs 24 to which the other electrodes of thedevice are connected.

Supported by the stem 13 and column or standard 18 and constituting aunitary assembly therewith is an axially symmetrical electrode systemfor producing a concentrated electron beam having a sharp clearlydefined spot focus upon the fluorescent screen 15.

In general, this electrode system comprises an electron source, acollimating system for concentrating the electrons emanating from thesource into an electron beam of small cross-section, a focussing systemfor bringing the electron beam to a sharp point focus upon the screenl6, and means for controling the direction or intensity or both of theelectron beam. More specifically, as shown in detail in Figs. 3 and 5,the electrode system comprises a cathode 25, a control or modulatingelectrode 26, a collimating electrode 21, a cylindrical focussingelectrode 28 and a dished focussing electrode 29. The direction of theelectron beam may be controled by pairs of parallel deflector plates 30and 3|, one pair being mounted at right angles to the other and theplates of each pair being equally spaced on opposite sides of thelongitudinal axis of the electrode system.

The cathode 25, as shown clearly in Fig. 5, may be of the indirectlyheated equipotential type, and comprises an elongated metallic sleeve toone end of which a metallic cap 32 is secured, like cap having the basesurface 33 thereof coated with a thermionic material. The cathode sleeveencompasses an insulating, preferably ceramic, core 34 in which a heaterfilament 35 is embedded, the inner end of the filament 35 beinginsulated from the cap 32 by an insulating plug or insert 36. The core34 is fitted in a central aperture in an insulating, preferably ceramic,platform or spacer 31. Electrical connection to the filament 35 and tothe cathode may be established through leading-in conductors 38 and 39,respectively, sealed in the press l4 and connected to appropriate onesof the terminals 20. The cathode may be anchored in position by theleading-in conductor 39, which is fitted in an aperture in the platform31 and cemented to the platform as indicated at 40 in Fig. 5.

The cathode 25 is encompassed by a cylindrical metallic sleeve 4|positioned in exact coaxiality with the cap 32 and abutting the platform31 at the base of a recess in one surface of the platform. As indicatedat 42 in Fig. 5, the sleeve 4| may be cemented to the platform 31 andfurther locked in position by a bent leading in conductor 43, which isfitted in an aperture in the platform, embedded in the press l4 andconnected to one of the terminal prongs 20.

The control or modulating electrode 26, which may be machined from ametallic block such as nickel, is fitted in the end of the metallicsleeve 4| and secured, as by welding, to the sleeve 4|.

As illustrated in Fig.- 5, the electrode 26 has an inner frustoconicalsurface 44 coaxial with the cap 32.

The collimating electrode 21 and cylindrical focussing electrode 29 aremounted coaxially with the modulating electrode 26 and cap 32 and aresupported as a unit by a pair of metallic standards or uprights 45extending from split metallic bands or collars 45 clamped about the stemI3, the standards or uprights 45 being afflxed, as by welding, to thecylindrical portion 41 of a metallic coupler in which the electrode 28is fitted, as shown clearly in Fig. 5.- The collimating electrode 21 maybe machined from a metallic block, for example of cold rolled steel, andhas a central aperture 48 and a convex surface 49 coaxial with andopposite the surface 44. The opposed surfaces 44 and 49 are ofaccurately predetermined configuration, as described in the applicationof Myron S. Glass identified hereinabove, whereby the field therebetweenis such as to concentrate the electrons emanating from the cathodesurface 33 into a thin beam entering the aperture 48.

As pointed out in the aforenoted application of Myron S. Glass,production of the fields requisite for the attainment of the desiredelectron concentration requires that the surfaces 44 and 49 beaccurately coaxial 'and symmetrical with respect to the common axis. Itwill be apparent from Fig. 5 that such accurate coaxiality cannot beobtained by usual methods, such as sighting, because the collimatingelectrode blocks the view into the frustoconical aperture in themodulating electrode 26. The accurate coaxiality is obtained, however,in accordance with one feature of this invention as will be clear fromthe following description.

Secured to the insulating member 31, as by a plurality of rivets oreyelets 50, and in exact coaxiality with the cylindrical sleeve 4| is aflanged circular metallic guide having a cylindrical upstanding portion5| and a laterally extending fiange 52. A plurality of resilient fingersor clips 53 are affixed to the flange 52, as by welding. Fitted betweenthe cylindrical portion 5| and the fingers or clips 53 is a cylindricalmetallic member 54 in which the electrode 21 is fitted and to which itis secured, as by welding. The end of the member 54 may be fitted in andsecured to a depending cylindrical portion 55 of the coupler member.

In the assembly of the device, the cylindrical sleeve 4| with themodulating electrode 26 thereon and the flanged guide 51, 52 are afiixedto the insulating member 31 in accurate coaxial relation. The electrodes21 and 28, cylinder 54, coupler member, supports 45 and bands or collars46 are fabricated into a unitary assembly, the spring clips 53 areaffixed as by welding to the cylinder 54, and the cylinder 54 is thenslipped over the flange 5|, the clips 53 are afiixed as by welding tothe flange 52 and the bands or withthe modulating electrode 28.

" It is highly desirable, of course, that the aperture in thecollimating electrode 21 through which the electron beam passes beaccurately alined with the cathode surface 33 and be on the axis ofsymmetry of the surfaces 44 and 49. Furthermore,

as pointed out in the aforenoted application of 29 byaplurality ofresilient metallic fingers I0. which are secured at one end, as bywelding, to the cylindrical shield 86 and bear against the coating.

A centrally apertured insulating, preferably ceramic, platform or discll supports the deflector plates 29 and 3|, is seated upon the edge ofthe cylindrical shield 66 and is locked against this Myron 8. Glass,preferably this aperture. should ture 01' this invention, the desiredaperture properly located is achieved readily. As shown in Fig.

6, the aperture 49 in the collimating electrode 21 is made of relativelygreat diameter and the walls thereof are provided with shoulders 58 and51. A length of tubing 58 having'a cap 59 afiixed there.- to is fittedin the aperture 48 with the edge of the cap 59 abutting the shoulder 56and the tubing is spun over as indicated at 60 to lock the tubing in theaperture 18. The cap 59 is provided with a central aperture SI of thedesired shape and dimension, for example circular and of the order of 10mils in diameter.

It will be noted that the cathode 25, modulating electrode 25,collimating electrode 21 and focusing electrode 28 together with theinsulating spacer II and coupler 41, 55 constitute a unitary V assemblywhich'is supported by the bands or collars l8 clamped about the stem l3,so that but small stresses are produced in the leading-in conductors 38,39 and I3, and, consequently, imilarly small stresses obtain in the armsof the press ll whereby cracking 'or breaking of the stem is prevented.

A suitable positive potential may be applied. to the electrodes 21 and28 through a leading-in conductor 62 embedded in the press and connectedto one of the standards or uprights 45 by a tie wire Ill.

A second unitary assembly comprising the focussing electrode 29 andthedeflector plates 30 and 3| is supported upon the tubular column 18 asbest shown in Fig. 3. This assembly includes a dished metallic basemember 53 which is seated upon the inner end of the column l8 and heldthereagainst by a plurality of arms 64 carried by and extending from asplit metallic band 55 clamped about the column is. The focussingelectrode 29 is provided with an integral cylindrical portion 65'fittedinthe dished member 63, is coaxially positioned with the cylindricalelectrode 28 and is provided with a central aperture 81 through whichthe electron beam passes. The surface 69 of the focussing electrode 29is of acedge as by a plurality of wires 12 securedto the shield,extending throughthe platform or disc and bent over against the platformor disc. Each of the deflector plates 30, and 9| .has an edge seated ona chordal groove or slot in the platform or disc II and is provided withextensions 13 which extend through slots in the platform and are twistedto hold the plates 30 and 3| securely in position. Each of the deflectorplates 30 and 3| is provided also with an extension 14 to which aleading-in conductor 15, connected to a corre-. sponding one of theterminals 24, is afiixed. The extensions 14 on the deflector plates 30extend through apertures 15 in the cylindrical member 56.

The cylindrical member 66. it will be noted, surrounds the deflectorplates 3ll and screens these plates and also the beam passingtherebetween from extraneous fields.

Seated upon the focussing electrode 29 is a centrally aperturedmetallicbarrier or baflle 11, which is coaxial with the focussingelectrode 29 and screens the focussing field, between the focussingelectrodes 28 and 29, from potentials upon the deflector plates.

As illustrated in Fig. 7, the deflector plates 3| also may bescreenedfrom extraneous fieldsby .a metallic shield including a cylindricalportion 18- and a centrally apertured top plate 19 which curatelydetermined configuration, as described Electrical connection to theelec-v "is held in position by a centrally apertured cap against theplatform. Also, as shown in Fig. 7,

the resilient fingers ll may be the arms of a hair-" pin shaped wireelement carried by an insulating,

preferably ceramic, member 90 mounted on a bracket 82 secured to thecylinder 66. The fingers H may be connected electrically to terminals 20or 24 by conductors 83 whereby the coating I! may be used as anaccelerating electrode.

In the modification illustrated in Fig. 8. an auxiliary pair ofdeflector plates 84 are provided within the shield 66 to enable controlof the deflection sensitivity of the device. Each of the deflectorplates 94 is coplanar with a corresponding one of the deflector plates30 and is supported therefrom through wire stubs 85 embedded ininsulating beads 88. Suitable leading-in conduc tors, not shown, may beprovided for the auxiliary plates 84 and connected to terminals 24.

Although specific embodiments of this invention have been shown anddescribed, it will be understood, of course, that they are butillustrative and that various modifications may be made therein withoutdeparting from the scope and spirit of this invention as defined in theappended claims. I

What is claimed is:

1. A unitary electrode assembly for electron discharge devicescomprising a stem, a platform supported above said stem and having acentral aperture and a recess coaxial with said aperture,- guide meanscarried by said platform and coaxial with said aperture, a cathodefitted in said aperture, an electrode coaxial with said cathode andhaving a tubular portion seated in said recess and secured to saidplatform, and a second electrode having a tubular portion positioned bysaid guide means in coaxial relation with said cathode and said firstelectrode.

2. A unitary electrode assembly for cathode ray discharge devicescomprising a platform having a circular recess in one face thereof, acylindrical guiding member mounted on said platform coaxial with saidrecess, a cathode carried by said platform and coaxial with said recessand guiding member, a modulating electrode coaxial with said cathodehaving a tubular portion seated in said recess and positioned thereby,an electrode structure having a collimatlng portion opposite saidmodulating electrode and a cylindrical portion fitted to said guidingmember, and resilient means aiiixed to said platform and locking saidcylindrical portion to said guiding member.

3. A unitary electrode assembly in accordance with claim 2 wherein saidcollimating portion is provided with a central aperture countersunk atopposite ends, said assembly comprising also an insert fitted in saidaperture and having its ends locked to said countersunk ends, saidinsert having a laterally extending portion provided with a restrictedaperture in alignment with said cathode.

4. An electron gun for cathode ray discharge devices comprising a stem,an insulating platform having a central aperture and a recess coaxialwith said aperture, a guiding member secured to said platform and havinga cylindrical portion coaxial with said aperture, a cathode fitted insaid aperture, a control electrode having a tubular portion seated insaid recess and aiiixed to said platform, a unitary assembly including acollimatlng electrode, a cylindrical focussing electrode and acylindrical member, said cylindrical member being fitted on saidcylindrical portion, means locking said cylindrical member to saidcylindrical portion, and supporting means aflixed to said stem and tosaid unitary assembly.

5. An electron discharge device comprising an enclosing vessel having aninternal tubular column, and a unitary electrode assembly mounted onsaid column, said assembly including a base member, a cylindrical shieldcarried by said base member, an insulating platform supported by saidshield and ailixed thereto, a pair of deflector plates depending fromsaid platform and within said shield, and a second pair of deflectorplates extending front-said platform and supported thereon.

6. An electron discharge device in accordance with claim 5 comprising asecond cylindrical shield mounted on said platform and encompassing saidsecond pair of deflector plates.

7. An electron discharge device in accordance with claim 5 wherein saidplatform is provided with chordal slots in which said deflector platesare seated, each of said deflector plates having extensions projectingthrough said slots and anchored to said platform.

8. A cathode ray discharge device comprising an enclosing vessel havinga stem at one end and an interior tubular standard extendinglongitudinally of said vessel from adjacent said stem, a unitaryelectrode assembly within said standard including a cathode and control.collimatlng and focussing electrodes coaxial with one another, aplatform having a central aperture in which said cathode is fitted, andhaving also a recess in one surface coaxial with said cathode, saidcontrol electrode including a tubular portion seated in said recess,guiding means afflxed to said platform and having a tubular membercoaxial with said aperture, said collimatlng electrode having a tubularportion fitted on said tubular member, means afllxing said tubularportion to said tubular member, and means supporting said focussingelectrode upon said tubular member and in coaxial relation therewith,means supporting said unitary assembly from said stem, a second unitaryassembly including a base member, a second focussing electrode carriedthereby, a second platform supported from said base member, and pairs ofdeflector plates mounted on said second platform, and means supportingsaid second assembly on said standard coaxial with said first assembly.

STURE O. EKSTRAND.

